Fast, Ultrasensitive Detection of Reactive Oxygen Species Using a Carbon Nanotube Based-Electrocatalytic Intracellular Sensor.

Herein, we report a highly sensitive electrocatalytic sensor-cell construct that can electrochemically communicate with the internal environment of immune cells (e.g., macrophages) via the selective monitoring of a particular reactive oxygen species (ROS), hydrogen peroxide. The sensor, which is based on vertically aligned single-walled carbon nanotubes functionalized with an osmium electrocatalyst, enabled the unprecedented detection of a local intracellular "pulse" of ROS on a short second time scale in response to bacterial endotoxin (lipopolysaccharide-LPS) stimulation. Our studies have shown that this initial pulse of ROS is dependent on NADPH oxidase (NOX) and toll like receptor 4 (TLR4). The results suggest that bacteria can induce a rapid intracellular pulse of ROS in macrophages that initiates the classical innate immune response of these cells to infection.

Electronic communication of cells with a surface mediated by boronic acid saccharide interactions.

The fabrication of a molecularly tailored surface functionalised with a saccharide binding motif, a phenyl boronic acid derivative is reported. The functionalised surface facilitated the transfer of electrons, via unique electronic interactions mediated by the presence of the boronic acid, from a macrophage cell line. This is the first example of eukaryotic cellular-electrical communication mediated by the binding of cells via their cell-surface saccharide units.

Real-time electrocatalytic sensing of cellular respiration.

In the present work we develop a real-time electrochemical mediator assay to enable the assessment of cell numbers and chemical toxicity. This allowed us to monitor metabolism down to a single cell in a low cost easy to use rapid assay which is not possible with current technology. The developed assay was based on the determination of oxygen. This was made possible via the use of electrochemical mediator ferrocene carboxylic acid (FcA). The FcA showed distinctive catalytic properties in interacting with reactive oxygen species generated from oxygen when compared to ferrocene methanol (FcMeOH). A deeper insight into the chemistry controlling this behaviour is provided. The behaviour is then taken advantage of to develop a cellular aerobic respiration assay. We describe the properties of the FcA system to detect, in real-time, the oxygen consumption of Escherichia coli DH5-α (E. coli). We demonstrated that the FcA-based oxygen assay is highly sensitive, and using a population of cells, oxygen consumption rates could be calculated down to a single cell level. More importantly, the results can be accomplished in minutes, considerably outperforming current commercially available biooxygen demand assays. The developed assay is expected to have a significant impact in diverse fields and industries, ranging from environmental toxicology through to pharmaceutical and agrochemical industries.

Regucalcin (RGN/SMP30) alters agonist- and thapsigargin-induced cytosolic [Ca2+] transients in cells by increasing SERCA Ca(2+)ATPase levels.

Regucalcin (RGN), also reported as senescence marker protein-30 (SMP30), plays a role in Ca(2+) homeostasis by modulating a number of Ca(2+)-dependent proteins. RGN also plays a cyto-protective role and its decrease is linked to age-related diseases and cell death. This study shows that RGN reduces agonist (histamine)-induced Ca(2+) transients in RGN(+) transfected COS-7 cells (RGN(+)) and also increases their Ca(2+) storage capacity. These observations are explained by RGN(+) cells having increased mRNA and protein expression levels of sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA). Therefore down-regulation of RGN expression may contribute to characteristics of age-dependent Ca(2+) homeostasis dis-regulation, by decreasing SERCA levels.

Simultaneous detection of MDR1 and WT1 gene expression to predict the prognosis of adult acute lymphoblastic leukemia.

The interaction between Wilms tumor gene 1 (WT1) and the promoter region of the multidrug resistance-1 (MDR1) gene has been previously reported but the clinical significance of the coexpression of WT1 and MDR1 in acute lymphoblastic leukemia (ALL) is still largely unknown. In this study, the expression levels of WT1 and MDR1 mRNA in 57 adult ALL patients were simultaneously detected using multiplex fluorescence real-time quantitative polymerase chain reaction. The expression levels of WT1 and MDR1 in bone marrow samples of adult ALL patients were significantly higher than those in the normal samples (P<0.001), and in addition, the expression levels of WT1 and MDR1 mRNA were highly correlated (r(s)=0.404, P=0.002). According to the expression levels of these two genes, the patients in this study were subdivided into the following three groups: low-WT1/low-MDR1 (n=16), high-WT1 or high-MDR1 (n=24), high-WT1/high-MDR1 (n=17). There was no significant difference in response to induction therapy among these three cohorts (P=0.217). The overall first year relapse rate was 53.2% (25 out of 47 ALL patients). High-WT1/high-MDR1 mRNA expression was strongly associated with BCR-ABL expression and a higher tendency to be T-cell ALL type. In addition, high-WT1/high-MDR1 have a significantly higher relapse rate (P=0.048) and shorter disease free survival (P=0.016). Our data suggests that high-WT1/high-MDR1 levels of mRNA expression may be associated with relatively poorer outcomes in patients with ALL. Therefore, the expression of WT1 and MDR1 may provide useful information for clinical decision.